Outdoor electronic sign enclosure

ABSTRACT

An outdoor electronic sign enclosure includes a sealed housing. A heat exchanger forms a part of the sealed housing. An air circulation system is coupled to the heat exchanger.

RELATED APPLICATIONS

[0001] This application claims priority from provisional application No. 60/392,954, which was filed on Jul. 1, 2002 and is assigned to the same assignee as the present application.

FIELD OF THE INVENTION

[0002] The present invention relates generally to the field of outdoor signs and more particularly to an outdoor electronic sign enclosure.

BACKGROUND OF THE INVENTION

[0003] Outdoor advertising and informational signs often contain electronic circuits, electrical motors, lights (LEDs) and other devices that fail or have significantly reduced lifetimes when the temperature of the sign is too high. The solar heating of signs can cause the interior of a sign to reach temperatures as high as 160 degrees Fahrenheit or higher. The solution has been to use fans to pull cool outside air over the sensitive electronics or even to add air conditioning systems to the sign. The first system requires high maintenance air filtering systems to eliminate the dust and debris that would otherwise enter the sign enclosure and potentially damage the electronics. The second system has high electric service cost and is prone to failures. In addition, both systems require a sign enclosure large enough to hold these cooling systems.

[0004] Thus there exists a need for improved sign housing that does not require the expensive cooling systems of prior art signs.

SUMMARY OF INVENTION

[0005] An outdoor electronic sign enclosure includes a sealed housing. A heat exchanger forms a part of the sealed housing. An air circulation system is coupled to the heat exchanger. In one embodiment the air circulation system is a fan. The fan is inside the sealed housing, in another embodiment.

[0006] In one embodiment, the heat exchanger is an accordion heat exchanger. The accordion heat exchanger may be shaded from the sun.

[0007] In one embodiment an electronic circuit board is included in the sealed housing.

[0008] In another embodiment, a mask covers at least a part of a face of the sealed housing.

[0009] In one embodiment, the sealed housing has a surface area of less than five square meters.

[0010] In one embodiment, an outdoor electronic sign enclosure has an sealed housing. An electronic circuit board is contained in a sealed housing. A heat exchanger forms a part of the sealed housing. In one embodiment, the sign enclosure includes an air circulation system. In another embodiment, the air circulation system is a fan. In one aspect of the invention, the fan is inside the sealed housing.

[0011] In one embodiment, the heat exchanger is an accordion heat exchanger.

[0012] In another embodiment, the sign has a mask.

[0013] In one embodiment, an outdoor electronic sign enclosure includes a sealed housing. A low energy lighting system is contained in the sealed housing. A heat exchanger forms part of the sealed housing. In one embodiment, the low energy lighting system is an electric lighting system. In one aspect of the invention, the low energy lighting system is a low voltage electric lighting system.

[0014] In one embodiment, the heat exchanger is an accordion heat exchanger. In another embodiment, the sign enclosure includes an air circulation system.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is an example of an outdoor sign in accordance with one embodiment of the invention;

[0016]FIG. 2 is a schematic diagram of an outdoor electronic sign enclosure in accordance with one embodiment of the invention;

[0017]FIG. 3 is a partial cross sectional view taken along the A-A line of FIG. 2;

[0018]FIG. 4 is a cross sectional view of an outdoor electronic sign enclosure in accordance with one embodiment of the invention; and

[0019]FIG. 5 is a front view of a mask in accordance with one embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 is an example of an outdoor sign 10 in accordance with one embodiment of the invention. In this case the sign 10 is an informational sign. The sign 10 may contain LEDs (light emitting diodes) 12 that are used to spell out words, such as “Stop Ahead”. Control and drive electronics are required to turn on and off the LEDs. Note that the invention is not limited to signs using LEDs but may be used with any display mechanism. The control electronics are contained in the housing 14 of the sign 10. The housing 14 has a front face 16, a back face 18 and four perimeter faces 20.

[0021]FIG. 2 is a schematic diagram of an outdoor electronic sign enclosure 30 in accordance with one embodiment of the invention. The enclosure 30 has a housing 32 which may be formed of aluminum or other sturdy material. The housing 32 is designed to be sealed. Sealed means that the interior 34 of the sign enclosure 30 is essentially sealed from dirt, debris, water and is weather tight. A heat exchanger 36 forms a part of the sign housing 32. The heat exchanger 36 is a passive device that allows the heat in the interior 34 of the housing to be dissipated into the surroundings. The heat is mainly generated by the solar loading on the sign. An air circulation system 38 causes hot air to flow over the heat exchanger 36 and be cooled. The air circulation system 38 is shown as a fan 40 and plenum 42. However, the air circulation system 38 may be a passive design in some operational environments. In one embodiment, another fan 41 and plenum 43 may be placed on the outside of the sign housing 32 to circulate cool ambient air over the outside of the heat exchanger 36.

[0022] The sign enclosure 30 may be used for any lighted system, however it is ideally suited for electronic light displays. Thus the sign enclosure 30 is shown to contain an electronic circuit board 44 connected to lights 46. Preferably the lights 46 are low energy lights, such as LEDs, and may also be low voltage lights (e.g., LEDs).

[0023]FIG. 3 is a partial cross sectional view taken along the A-A line of FIG. 2. The enclosure 30 includes a sealed housing 32. A part of the housing 32 is formed by an accordion heat exchanger 36. An accordion heat exchanger 36 is a sheet of metal (or other heat conductive material) that is formed into a repeating S-shape, V-shape, sine wave or other similar shape. This design has an advantage over other heat exchanger designs because it is light weight and inexpensive. The weight and cost of outdoor signs is a significant factor in their marketability. Other heat exchanger designs were considered and may be used, however none of those considered have this advantageous combination of low cost and weight. A fan 40 is placed inside the sealed housing 32 and forces hot air through a plenum 42 and over the heat exchanger 36 to be cooled. Note that the grooves 44 of the heat exchanger are arranged so that air from the fan 40 flows through the grooves. In this example the air from the fan 40 would flow out of the paper along the grooves 44. Field tests showed that a sign enclosure using the techniques shown in FIG. 3 had half the temperature rise as a sign housing without the heat exchanger and fan.

[0024] In one embodiment, the heat exchanger 36 is placed on a bottom of the enclosure. This shades the heat exchanger 36 from the sun.

[0025]FIG. 4 is a cross sectional view of an outdoor electronic sign enclosure 30 in accordance with one embodiment of the invention. In this embodiment, there are three heat exchangers 36, 50 & 52. Note that the wavy shape of the heat exchanger is meant to represent the heat exchanger. In practice the grooves are aligned with the air flow, so that air may flow along the grooves. Two of the heat exchangers 50 & 52 are placed on the side walls of the housing 32. These heat exchangers 50 & 52 are covered by shields 54 & 56. In one embodiment, the shields 54, 56 are half pipes of thin metal. The shields deflect the sun and provide a conduit or plenum for air to flow through. In one embodiment a pair of fans 58, 60 are placed in the conduits and force outside air to flow over the heat exchangers 54, 56. This embodiment, provides additional cooling in areas with particularly high temperatures and high solar loading. In another embodiment a fan 61 and shield 61 are placed on the outside of heat exchanger 36 FIG. 5 is a front view of a mask 70 in accordance with one embodiment of the invention. The mask 70 has a plurality of holes 72 through which the lights inside the enclosures may be seen. The mask 70 covers all areas where there are no lights in the front face of the sign enclosure. The mask 70 further reduces the solar loading on the sign by shielding the suns rays from the inside of the sign housing.

[0026] Thus there has been described an outdoor electronic sign enclosure that does not require expensive and bulky air filtering or air conditioning systems. The invention uses a sealed housing that virtually eliminates dirt, debris and water that can ruin or significantly reduce the life of sensitive electronics. The cooling system is able to reduce the excessive heat that might also reduce the life of the electronic components. This system is considerably less expensive to build, maintain and operate than prior art outdoor electronic signs. This design is ideally suited for smaller outdoor signs, for examples signs having an area of five square meters or less.

[0027] While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alterations, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alterations, modifications, and variations in the appended claims. 

What is claimed is:
 1. An outdoor electronic sign enclosure, comprising: a sealed housing; a heat exchanger forming a part of the sealed housing; and an air circulation system coupled to the heat exchanger.
 2. The sign of claim 1, wherein the air circulation system is a fan.
 3. The sign of claim 2, wherein the fan is inside the sealed housing.
 4. The sign of claim 1, wherein the heat exchanges is an accordion heat exchanger.
 5. The sign of claim 4, wherein the accordion heat exchanger is shaded from the sun.
 6. The sign of claim 1, further including an electronic circuit board in the sealed housing.
 7. The sign of claim 1, further including a mask covering at least a part of a face of the sealed housing.
 8. The sign of claim 1, wherein the sealed housing has a surface area of less than five square meters.
 9. An outdoor electronic sign enclosure, comprising: a sealed housing; an electronic circuit board contained in the sealed housing; and a heat exchanger forming a part of the sealed housing.
 10. The sign of claim 9, further including an air circulation system.
 11. The sign of claim 10, wherein the air circulation system is a fan.
 12. The sign of claim 11, wherein the fan is inside the sealed housing.
 13. The sign of claim 12, wherein the heat exchanger is an accordion heat exchanger.
 14. The sign of claim 13, wherein the sign has a mask.
 15. An outdoor electronic sign enclosure, comprising: a sealed housing; a low energy display system contained in the sealed housing; and a heat exchanger forming part of the sealed housing.
 16. The sign of claim 15, wherein the low energy lighting system is an electric lighting system.
 17. The sign of claim 16, wherein the low energy lighting system is a low voltage electric lighting system.
 18. The sign of claim 15, wherein the heat exchanger is an accordion heat exchanger.
 19. The sign of claim 15, further including an air circulation system.
 20. An outdoor electronic sign enclosure, comprising: a sealed housing; a heat exchanger attached to the sign housing; and a mask face on a face of the sealed housing.
 21. The sign of claim 20, wherein the heat exchanger is an accordion type heat exchanger. 